A terminal is known for having a touch panel that detects a plurality of contact coordinates. Such touch panels include, for example, an electrostatic capacitance type touch panel for detecting a change in capacitance.
A patent literature describes an input device set placed on a touch panel for inputting coordinates into the touch panel. Such input device set is a collection of input devices provided with specific information of “”, “”, “”, “”, “” . . . , and a group of specific information items forms a system of hiragana, for example. A bottom surface of each input device has a plurality of contact parts for touching a placing surface of the touch panel. The contact parts are respectively disposed in predetermined areas selected from divided areas of a bottom surface. Arrangement patterns of contact parts differ depending on input devices. The terminal identifies an input device according to an arrangement pattern of contact parts, and is able to obtain specific information provided to the input device.
A contact surface which has a predetermined area, such as a fingertip, needs to touch a placing surface of the touch panel in order to input coordinates into a touch panel. As such, the area of the bottom surface of the input device needs to be expanded to increase the number of the divided areas in order to increase the number of specific information items. This increases a size of the input device. However, in view of operability, the input device is preferably in a size that could be handled with one hand. For example, when a child uses an input device, the input device should be made as small as possible. Accordingly, for conventional input devices, it is difficult to increase both the number of specific information items and operability of the input device.